1. Field of the Invention
The present invention relates to a liquid processing apparatus for performing a predetermined liquid process on a substrate, such as a semiconductor wafer.
2. Description of the Related Art
In the process of manufacturing semiconductor devices or flat panel display devices (FPD), liquid processes are frequently used, in which a process liquid is supplied onto a target substrate, such as a semiconductor wafer or glass substrate. For example, processes of this kind encompass a cleaning process for removing particles and/or contaminants deposited on a substrate, and a coating process for applying a photo-resist liquid or development liquid in a photolithography stage.
In general, an apparatus of this kind is arranged to supply a process liquid onto the center of a wafer, and rotate the wafer to spread the process liquid outward, thereby forming a liquid film and throwing off the process liquid. A surrounding member, such as a cup, is disposed around the wafer to guide downward the process liquid thrown off from the wafer, so that the process liquid is swiftly drained. However, where such a cup or the like is used, part of the process liquid may bounce back to the wafer as mist, and generate defects thereon, such as water marks and/or particles.
As a technique for preventing this problem, Jpn. Pat. Appln. KOKAI Publication No. 8-1064 (Patent Document 1) discloses a technique which utilizes a process liquid receiving member to be rotated integrally with rotary support means that rotates along with a substrate held thereon in a horizontal state. The process liquid receiving member receives a process liquid scattered around the substrate, and guides the process liquid outward to collect it. According to Patent Document 1, the process liquid receiving member includes a horizontal eaves portion, an inclined guide portion for guiding the process liquid outward and downward, a horizontal guide portion for guiding the process liquid outward in the horizontal direction, and a wall portion extending upward in the vertical direction, in this order from the substrate side. With this arrangement, the process liquid is guided into a narrow space to prevent mist from bouncing back onto the substrate, while the process liquid is drained from a drain port formed at a corner of the process receiving member. The process liquid is then discharged through grooves extending outward within a spacer disposed around the process liquid receiving member.
However, in the case of the technique disclosed in Patent Document 1, the process liquid is guided into a narrow space around the substrate by the process liquid receiving member that rotates along with the substrate. Accordingly, the spacer portion around the substrate needs to be larger and increases the foot print of the apparatus. Further, since exhaust gas is discharged along with drainage, it is necessary to dispose a mechanism for separating the exhaust gas and drainage on the downstream side. In order to separate exhaust gas and drainage without using a mechanism for separating them, it may be possible to separately dispose an exhaust cup and a drain cup. However, if the exhaust cup and drain cup are simply separately disposed, the foot print of the apparatus is further increased.
Where gasified components of a process liquid is exhausted from around a process liquid receiving member, it is necessary to receive the gasified components by an annular exhaust cup and discharge the gasified components smoothly and uniformly from all around through an exhaust port or exhaust ports formed at one or several positions. However, Patent Document 1 is silent about techniques for performing such exhaust.
On the other hand, in general, a drain cup for receiving drainage is annular, made of a synthetic resin, and fixed by appropriate means. The annular drain cup receives, from a rotating process liquid receiving member, a process liquid, which may have a relatively high temperature of, e.g., 80° C. When the drain cup, made of a synthetic resin, receives such a process liquid, the drain cup is thermally expanded to a large extent. Consequently, depending on the mounting manner of the drain cup, the thermal expansion may be insufficiently absorbed, thereby damaging the drain cup.
In the case of a liquid processing apparatus of the type that rotate a substrate held in a horizontal state, if the position of the substrate is shifted during rotation, problems, such as substrate damage, may be caused. Accordingly, there is known a substrate holding member provided with holding accessories (chuck) for holding the outer edge of the substrate, so that the substrate is reliably fixed to and integrally rotated with the substrate holding member (for example, Jpn. Pat. Appln. KOKAI Publication No. 2002-368066 (Patent Document 2: FIG. 15 and so forth)).
In the liquid processing apparatus disclosed in Patent Document 2, the holding accessories are disposed at several positions to extend below the substrate holding member on the lower side, and respectively include portions for holding the outer edge of a substrate on the upper side. When the substrate holding member provided with these holding accessories is rotated, portions of the holding accessories extending downward from the substrate holding member generate stray winds below the substrate holding member. The stray winds may affect an exhaust gas flow below the substrate holding member and hinder mist from being discharged, thereby causing mist to bounce back to the front surface of the substrate, and generate defects thereon, such as water marks and/or particles. Further, stray winds generated below the substrate holding member may affect a drainage flow of a process liquid in a drain cup and hinder the process liquid from efficiently flowing into a drain port.